The operation of electronic components can be disrupted by the environment in which they operate, ex. an artificial or natural radiation environment or an electromagnetic environment. Harmful external factors trigger the creation of parasitic currents by interacting with the material that makes up the component. These may cause the temporary or permanent malfunction of the component and the application that uses it.
In a natural radiation environment, these effects, generally called singular effects, are created by particles. For example, heavy ions and protons in space affect the electronic equipment in satellites and launch vehicles. At the lower altitudes where airplanes operate, there is an especially high presence of neutrons, which also create singular effects. On the ground, such harmful factors can also be found and can affect electronic components, whether due to particles in the natural environment, radioactive particles in the boxes, or the immunity, signal integrity, thermal instability, or method. In the rest of the text, the effects of particles will be addressed more specifically, but the invention remains applicable to the same types of effects created by various diverse environments.
The physical phenomena responsible for failures caused by harmful external factors are rather varied. It is possible, however, to identify several major categories of failures. The invention applies particularly to some of the effects caused by the radioactive or electromagnetic environments that are produced by the combined action of creating parasitic currents and amplifying or maintaining these parasitic currents.
For example, a global or localized triggering of a parasitic thyristor, called a latchup or Single Event Latchup (SEL), in a part of the component (then called a microlatchup), a triggering of a parasitic bipolar transistor, called snapback or SES, a failure involving the combined action of triggering a parasitic bipolar structure and the amplification or maintenance of the parasitic current, called Single Event Burnout (SEB). These effects may or may not be destructive to the component.
More specifically, the interaction of a particle or radiation with the material may result in the creation of electron charges or holes. Under certain conditions, these charges can trigger one or more parasitic structures. These structures are called parasitic because, although they exist in the component intrinsically, they are never activated when the component is operating normally.
The conditions that produce these triggers are mainly related to the amount of charge generated, the location, and the type (spatial and temporal) for the generated charge.
However, most of the time, the triggering of these parasitic structures, resulting from the generation of charges, is not enough to cause the component to fail. A second phenomenon can maintain or amplify the parasitic current generated by the first phenomenon. The triggering of this second phenomenon is primarily linked to the component's intrinsic characteristics (doping level, physical organization of the component, etc.) and operation conditions, particularly its polarization, frequency, temperature.
For example, an SEB phenomenon can be triggered in power components. These include, for example, MOS power field-effect transistors MOSFET, insulated gate bipolar transistors IGBT, power diodes, and others. For example, FIG. 1 shows, for such a polarized (positive drain-force voltage) n-type silicon technology MOSFET power transistor that is initially blocked and has a parasitic bipolar structure, that the (direct or indirect) action of a particle from the natural radiation environment with the silicon that makes up the transistor results in the creation of a number of electron-hole pairs in the component. Under the influence of electrical fields and diffusion, these charges move, which generates a parasitic current within the structure. Under certain conditions, particularly where the charges are generated and the amount of charge generated, the parasitic current can pass directly through an originally blocked source/caisson junction. To the extent that the source/caisson junction can be passed through and although the caisson/drain junction is polarized in reverse, a source/caisson/drain parasitic bipolar transistor is triggered. The source is a transmitter, the caisson is the base, and the drain is the collector. In the absence of amplification and maintenance phenomenon, this parasitic structure remains able to be passed through while the charges generated by the particle/silicon interaction are drained. It is then blocked again, and the component returns to its normal operation. However, depending on certain parameters, particularly the polarization voltage applied to the drain, the temperature, and the internal technology of the component, the conditions may be satisfied so that local impact ionization occurs initially at the caisson-drain junction (highly polarized in reverse) and allows the amplification and maintenance of the parasitic current in the source-caisson-drain parasitic bipolar structure. Generally in the absence of protection, the amplification of the parasitic current causes the destruction of the component.
This example shows that the SEB phenomenon is indeed triggered by the combined action of both phenomena: the triggering of a parasitic structure and the amplification/maintenance of the parasitic current.
The physical nature of the initial parasitic current's amplification and/or maintenance phenomena varies according to the type of radiation effects and the type of components. In the case of the SEB phenomenon, it is an amplification/maintenance of the current due to the impact ionization. In the case of the SEL phenomenon, for CMOS technologies, the current amplification/maintenance happens by the triggering of a parasitic bipolar structure combined with the first, and the results may be temporary, permanent, or destructive.
Currently, there is no way to measure polarization voltage or any other characteristics of use, frequency, temperature, pressure, magnetic field value, or other factors, below which a component may no longer be subject to triggering such parasites.